1. Field of the Invention
This invention relates generally to providing laser level planes, and more particularly to laser level plane apparatus incorporating self-leveling devices.
2. Description of the Related Art
In the recent past, laser level devices have been used to determine level horizontal or plumb vertical planes for construction, surveying, remodeling, etc. To determine truly horizontal plane, for example, conventional laser level devices typically direct a vertical light beam from a light source through a collimating lens and into a rotating optics such as a rotating pentaprism. The rotating pentaprism then redirects the vertical light beam approximately 90 degrees to sweep out a level horizontal plane of light. An electronic receiver is typically set up to receive and detect the beam thereby providing a reference level plane.
During the course of usage however, laser level devices can often become tilted or uneven, for example, through bumping. When the devices become tilted or uneven, the vertical light beam tilts as well. Since the rotating pentaprism redirects the light beam by a fixed 90 degrees, tilted or uneven laser level devices generally cannot project a level horizontal plane accurately.
In response, laser level devices can include self-leveling mechanisms to compensate for tilting. An example of one such self-leveling laser level device is found in U.S. Pat. No. 4,221,483, which describes a self-leveling portable laser beam level instrument. The instrument achieves self-leveling by mounting a collimating lens on a suspended compensator pendulum. The optical path of a laser beam from a beam source to a rotating pentaprism is vertical and the light source is concentric with the center of the compensator pendulum. The suspended collimating lens collimates the laser beam from the beam source and at the same time compensates for a tilt to maintain the beam in a truly vertical direction for projecting a truly horizontal plane within a specified range of tilt.
Often however, a need arises for projecting a plumb (i.e., true) vertical plane as well as a level horizontal plane in the field. For example, a plumb vertical plane may be used for erecting vertical structures such as a wall or as a plumb to find the true vertical between two points during construction, surveying, remodeling, and the like.
Unfortunately, the conventional self-leveling laser devices with a collimating lens mounted on compensator pendulum typically cannot project a true vertical plane. This is because the direction of the light beam through the collimating lens in these devices is highly sensitive to the compensating pendulum. Specifically, when a conventional self-leveling laser device with a compensator pendulum is placed on its side, the compensator pendulum, and thus the mounted lens, collapse down onto the same side due to gravity. Hence, the light beam deviates due to the lateral position change, resulting in inaccurate vertical plane. To correct the inaccuracy, expensive kits specifically tailored to be used with these conventional devices have been utilized to generate a plumb vertical plane.
The compensator pendulums of conventional self-leveling devices generally comprise an inner cylinder disposed within a larger outer cylinder. In this configuration, the compensator pendulum may move in lateral directions. Hence, the path of the light beam, which depends on the lens concentrically mounted on the compensator pendulum, is highly sensitive on the position of the pendulum. Accordingly, when the device is laid on a side against a sidewall for vertical plane projection, the its light beam path is deviated, which typically causes inaccurate vertical plane.
Another problem associated with conventional laser level devices is their durability. For example, since portable laser level devices are routinely used in construction environment, they are prone to accidental drops. In particular, conventional laser level devices which utilize wires to suspend compensator pendulums are relatively sensitive to shocks. These wires are typically sensitive to shocks and may break when dropped on the ground.
In view of the foregoing, what is needed is a self-leveling laser level device and method that can project a vertical as well as a level horizontal plane without the expense of a costly kit. Further, what is needed is a self-leveling laser level device and method that is less sensitive on the position of the compensator pendulum in the lateral direction. In addition, what is also needed is a self-leveling laser device and method that provide durability against shocks.